Developing device for photoconducting materials

ABSTRACT

A developing apparatus for photoconductive materials, is formed of a storage tank for a supply of liquid developer with pigment particles. The developer liquid is pumped through a distributing channel and a calming chamber into an upwardly concave, shallow guide and the level of the developer liquid is determined by an overflow adjacent the outlet end of the guide from where it flows back into the storage tank. To provide nonturbulent supply, the developer flows from the distributing conduit into the guide below the level of liquid within the guide. The overflow or developer liquid outlet is formed by an edge of an upper guide element defining the guide channel. The components of the apparatus fit into one another for ease in assembly.

I United States Patent 1 3,592,165

[72} Inventors Karlllrendel (56] Relerencea Cited e st: UNITED STATES PATENTS 3,062,123 11/1962 Limberger LIB/637 (LX) ux 3,100,471 8/l963 Gutbier 1 1 1 113/429 ux 3.202.526 8/[965 Ostensen 118/637 (LX) ux 3,249,088 5/1966 Ostensen 113/429 )1 3,284,224 11/1966 Lehmann 1. 1.13/63? (1.21) ux 3,334,6l3 8/1967 Young 118/429 )1 ml PP 3,368,526 2/l968 MflISUmOIO e161 1. 118/429 x 523 3,317,933 4/l968 Zawiski ..l.l.8/637 (LX) ux 3 I in d-h 1 1 3 Primary Examiner Morris Kaplan Hub-I, Attorney-McGlew and Toren [32] Priority Mly2,l967 [33] Guam", ABSTRACT: A developing apparatus for photoconductive (31] P [5 72 389.4

materials, 1s formed of a storage tank for a supply of liquid developer with pigment particles The developer liquid is pumped through a distributing channel and a calming chamber into an upwardly concave, shallow guide and the level of the developer liquid is detennined by an overflow ad- DEVELOPING DEVICE FOR PHOTOCONDUCTING jacent the outlet end of the guide from where it flows back MATERIALS into the storage tank. To provide nonturbulent supply, the cm developer flows from the distributing conduit into the guide [52) U.5.Cl. 118/428 below the level of liquid within the guide. The overflow or [5|] Int. B054: 3/02 developer liquid outlet is formed by an edge of an upper guide [50] fleldolsenreh 118/428, element defining the guide channel. The components of the 403, 429, 424, 637; l 17/] l3-l l7; 95/89 L apparatus fit into one another for ease in assembly.

ATENTEU JUL 1 3:97;

SHEET 2 [1F 7 PATENTEU JULISB'II 13597165 SHEET 3 OF 7 Fig.3

PATENIEU JUL I 31% Fig.

PATENTED JUL 1 3 ran SHEET 5 0F 7 PATENIEU JUL? 3 I971 SHEET 7 OF 7 Fig.1!

DEVELOPING DEVICE FOR PHOTOCONDUCTING MATERIALS DESCRIPTION The invention relates to a developing apparatus for photoconductive material with a developing liquid tank and with curved guides.

The use of curve guides has the advantage of enabling a complete change of the developing liquid by pumping.

However, the resulting flows create problems from the viewpoint of the nonturbulant introduction of the developer and its uniform removal. ln known constructions, the developer is pumped in at the outlet end ofthe guide and flows off over the lower end wall of the guide or over a guide member forming this wall at the inlet end. This end, forming the overflow, is lower than the outlet end so that, particularly where the liquid is supplied from below through an upwardly open distributor, considerable turbulence is created by the directional change and by the decompression of the developer liquid in the distributor outlet, after the liquid has been compressed by the action of the pump in the conduit, Since the copying material passes through the developer in the guide generally with its coating facing upwards, the coating is pressed at the outlet against the upper guide member, giving rise to friction which might affect the developer powder distribution in the finished picture. In addition, irregular flow also results from the introduction of a sheet of copying paper at the inlet of the guide element, because the sheet blocks the overflow at least partly. After the leading edge of the sheet has passed beyond the point at which the developer is supplied, a large part of the developer liquid flows uselessly along the reverse side of the sheet, reinforcing the frictional contact between the picture side and the upper guide member and extending the contact path.

In addition, the known construction entails a flow of developer in countercurrent to the direction of movement of the coping material; hence, pigmentation particles already deposited on the copying material can thereby be dislodged.

it is an object of the invention to provide a developing device in which the drawbacks of known devices are eliminated, while maintaining the advantages of a channelshaped guide configuration, and providing a construction which facilitates the handling, the assembly of the parts, the changing of the developer, and the like.

It is another object of the invention, to provide a developing device of the kind hereinbefore specified, in which the supply of the developer from the distributing conduit to the guide channel for the copying paper is arranged below the developer liquid level in the guide, and the overflow is formed by at least one edge of an upper element defining the upper limit of the guide with the upper guide element channel being shorter than the lower guide element.

The introduction of the developer liquid below the liquid level in the guide ensures nonturbulent introduction without air inclusions and without segregation phenomena. The use of the upper guide element as an overflow surface enables the liquid to flow into a dish formed by the upper concave surface of the upper guide element. Thus, the overflow remains unaffected by the passage of the sheet of copying material, and the liquid leaves the copying material without transversely flowing thereover.

it is a further object of the invention to provide a developing device, in which the inlet end of the upper guide element into the guide channel is lower than the overflow or outlet end. Hence, the developing liquid flows, at least in section, in the same direction as the movement of the coping material and relative movement between the liquid and the copying material may be limited to a minimum at least within the section in which the copying material leaves, and the developing, especially of fine outlines, is much improved.

It is another object of the invention to provide a developing device, in which the distributing channel for the developing liquid is arranged above the guide for the copying material. in this construction, the developer is applied to the copying material above its exposed or coated surface, eliminating any pressure between the coated side of the copying sheet and the upper guide element, and enabling full use to be made of the liquid developer. In addition, crossflow and turbulence are also avoided, which occur where the liquid is forced to flow from one side of the copying material to the other.

It is another object of the invention to provide a developing device in which the distributing channel for the developing liquid is located adjacent to the inlet end of an upper guide element and terminates in at least one opening in the upper guide element, or wherein the distributing channel has a wall section, extending the guide for the copying material about the upper edge of the inlet in the upper guide element which has, in this case, a shorter construction than the lower guide element forming the lower surface of the guide. This construction ensures the full flow from the inlet to the outlet whilst maintaining the above-mentioned advantages.

This shorter construction of the upper guide element, at least at its outlet, has also the advantage that the copying material, leaving the liquid, finds an almost dry supporting surface, from which any entrained liquid can flow back into the container.

It is a further object of the invention to provide a developing device, comprising a calming chamber between the distributing channel and the inlet to the guide, and flaring outwardly from a connecting orifice to the distributing channel. This calming chamber improves the nonturbulent influx of the developer which reaches the calming chamber without any reversal of flow, while flow effects from the distributing chamber are reduced.

The opening from the calming chamber, extending preferably across the width of the guide, has the shape ofa slot and conveniently it has a smaller height than the connecting orifice or orifices between the calming chamber and the distributor channel. This, too, contributes to the nonturbulent introduction of the liquid into the guide and makes possible, in addition thereto, the venting of air from the developer, if the slot is lower than the connecting orifice. For purposes of venting, the calming chamber may be equipped with an upwardly directed hole, preferably at the end of a roof portion rising thereto.

it is a further object of the invention to provide a developing device, in which the connecting opening between the calming chamber and the distributing channel consists of several, preferably oblong, equidistantly spaced holes with vertical axes. This ensures the uniform supply of developing liquid into the calming chamber or possibly also directly into the guide. This effect may be further supported by connecting the distributing channel on one end with the delivery socket of the pump, supplying the developing liquid, while its other end is tapered.

it is a further object of the invention to provide a developing device, comprising a base, an upper guide element with at least upwardly extending wall sections for forming the channel and the calming chamber on the upper guide element, and a cover, having a wall section for extending the upper guide element at least in the region of an expanding orifice of the guide. This cover enables a constant pressure and a uniform influx to be obtained over the length of the tapering distributing channel, while the cover, adapted to be slid on or screwed on, may be fitted at different levels by means of intermediate sealing elements, such that this pressure can be controlled.

The cover for the distributing channel and the calming chamber may have a downwardly directed wall extending along a partition with upwardly extending open slots between the distributing channel and calming chamber and covering at least the top ends of the slots. The downwardly directed wall affords vertical adjustment of the connecting orifice between the distributor channel and the calming chamber for controlling flow therethrough. In a preferred embodiment, the underside of the upper guide element has longitudinal ribs, which are conveniently mounted on a metal guide member extending from the inlet side of the upper guide element for at least over a part of the length of the upper guide element within the guide channel. The metal guide member bridges a downwardly facing open cavity in the upper guide element which is located below the distributing channel. Since the guide element need not extend to the side edges, this cavity may also be used for venting and may be provided with an upwardly directed vent hole. Moreover, the section of the guide member which spans the cavity may be perforated. This is possible in conjunction with the construction according to the invention, because the copying material is guided through the liquid in the guide channel along the lower guide element.

It is a further object of the invention to provide a developing device, having a trough-shaped insert, the bottom of which forms the lower guide element, while the upper guide element is also a trough-shaped member provided with sidewalls and fitted into the lower guide element, wherein the two troughshaped inserts each have a recess along one edge and each of the recesses has two openings aligned with the openings in the other recess, one set of aligned openings serving as the inlet for the developing liquid and the other for its outlet and return to a storage tank; the first set of openings includes a seal connecting the openings while the other or second set of openings is provided with a socket arranged on the recess of the upper guide element and arranged to engage into the opening ofthe lower element, with this second set of openings arranged at the lowest part of the guide elements. Thus, during the assem bly, with the alignment of the openings parts are automatically located.

If the storage tank is formed by a trough-shaped base vessel, its bottom and/or sidewalls have guide means for receiving an intermediate base, forming an upwardly facing open dish, into which the inserts with the guide elements may be fitted from above so that the lower insert rests on webs of the intermediate base and the upper insert on the lower insert and on the intermediate base. This results in an assembly of three components arranged to fit into the storage tank, while protection against spillage is improved, as compared with known constructions, by fitting the intermediate base, which forms a continuous collecting surface, into the base vessel and thereby permits, in conjunction with an edge seal, a comparatively shallow construction of the storage tank.

It is known to form an intermediate base having transverse collecting trough with several holes. However, in a convenient manner intermediate base, according to the invention, comprises a downwardly extending collecting chamber having a connecting socket for the developer feed conduit to the dis' tributing channel, and another hole extends upwardly from the base, forming a collective discharge from the trough in the intermediate base.

It is a further object of the invention to provide a developing device, comprising a novel arrangement for a developing liquid pump which should not be connected with the guide elements, because these elements must be removed for cleaning occasionally, while the pump should be capable of being dismantled separately, without providing special mounting means for a closed housing. According to the invention, the base of the collecting chamber comprises a pump opening to which is connected a socket extending upwardly to about the level of the upper part of the upper insert, a pump shaft is located in the pump opening, while the intermediate base carries and forms a pump housing. Thus, the intermediate base forms practically a part of the pump housing, and, since the intermediate base is a separate component, the pump can be withdrawn together with it.

In a particularly simple construction, the pump housing forms a cover for the opening of the pump shaft and the opening to the developer feed to the distributing channel, and has an intake under the opening for the pump shaft.

In order to create stable conditions during assembly, and also with regard to the forces generated by the pump drive during operation, there are provided, in addition to rim supports, two centering members or lugs for the intermediate base on the bottom of the trough-shaped storage tank, and one i of these centering members is strip-shaped. The strip centering member extends in the direction of a line connecting the two centering lugs, while the other centering lug is pin-shaped and engages into the discharge hole in the bottom of the collecting chamber, and a slotted recess is provided for the first centering member in the intermediate base. The pin-shaped centering member is provided with a cross section which leaves the discharge hole free and unobstructed.

Preferably, the lugs and projections to be interconnected for fitting the parts together, and the intermediate base are retained by clips. In a preferred embodiment, the troughshaped storage tank has, on opposite walls, outwardly offset and downwardly extending webs with holes, and clamping means consisting of plastic hooks with a reversely bent leg are provided, which underlie the downwardly directed webs and engage into the holes of the webs by means of a projection. Thus, the device can be assembled without metal clips and the clamping effect is produced by the elasticity of the synthetic material.

A particular problem encountered in mounting shafts in tubular sockets of plastic material is that the bearing means must ensure the definite location of the shaft, and at the same time a certain adaptability must be provided in the support made of plastics or other materials so as to avoid excessive stresses during the mounting of the bearings. Such stresses may cause the shaft to jam, and may also lead to hairline cracks, particularly in synthetic resin supports.

Thus, according to a further feature of the invention, this problem is overcome by providing guide bushes for the pump shaft, in the form of two concentric, mutually spaced apart bushes, with the shaft running in the inner bush and the outer bush having circumferentially distributed mounting ribs, wherein both bushes are connected, at points between the ribs, by webs and these webs have conveniently at one end a ring forming an external flange. This ring serves as limit stop for fitting the bush into a tubular support, and may also be omitted, where the axial position of the bush is not relevant. Conveniently, three webs are provided, angularly spaced apart. Since the outer bush has a thinner wall that the inner bush, it can be deformed during its fitting into a support, in the zone between the webs, because only rectilinear support zones are provided and a deflection is possible between these zones. The centering of the inner bush is ensured by these webs. Conveniently the outer bush may be provided between the inner bush and the flanged ring, thus providing additional ventilatron.

Further features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings and from the appended claims. In the drawings:

FIG. 1 is a cross section ofa combined developing device, in accordance with the present invention, taken along the line 1-] in FIG. 2;

FIG. 2 is a cross section of FIG. 1 along the line Il-II;

FIG. 3 is a cross section along the line III-III in FIG. 2;

FIG. 4 is a cross section along the line IV-IV in FIG. 2-,

FIG. 5 is a cross section along the line VV in FIG. 1;

FIG. 6 is a cross section along the line VIVI in FIG. I;

FIG. 7 is a partial view of FIG. 4 viewed from below;

FIG. 8 is a top view ofa guide bush;

FIG. 9 is a side elevation of the guide bush of FIG. 8;

FIG. 10 is a view ot'the guide bush seen from below;

FIG. It is a cross section along he line XI-XI in FIG. 8.

In FIGS. I, 3, 4 and 7 the devices are represented with a break in the middle.

identical parts are marked with the same reference numerals in all figures. In the drawing a developing device is shown having a trough-shaped base portion 1, see FIG. 5, with a pair of vertically oriented longitudinally extending sidewalls 2, 3 with outwardly directed steps 4, 5, from which upper wall sections 6, 7 extend. The lower wall sections of the sidewalls extend upwardly and forms with the upper wall sections 6, 7 upwardly directed open longitudinal grooves 8, 9. An angled of L-shaped seal 10, ll fits into each of these grooves with a horizontal leg of the seal resting on the upper edge of a raised web l2, 13 located at the upper ends of the lower sections of the sidewalls 2, 3. It may be seen from FIG. I that the base portion 1 has another pair of sidewalls l4, l5 which have a corresponding configuration and receive L-shaped seals I6, I7.

As shown in FIG. 2 the upper wall sections 6, 7 are equipped at least in part below the steps 4, 5 with downwardly directed webs 18, 19 with holes 20, 2I passing therethrough and arranged in spaced relationship from the lower sections of the longitudinal sidewalls 2, 3. Clamping means are fitted into these webs as described further below. The outsides of the sidewalls are equipped with ribs 22, 23 covering the spaces behind the webs l8, 19 and laterally guiding the clamping means to be fitted.

An intermediate base 24, see FIG. 5, is mounted on the steps or seals 10, l l; below the lowest point ofa guide 69 to be hereinafter described, this intermediate base is dished downwardly between the sidewalls as at 25 and has at this point discharge holes 26, 27, see FIG. 3, extending across the direction of flow though the guide, and leading directly into a storage tank formed in the trough-shaped base portion 1.

Along its edges parallel to the sidewalls, the intermediate base 24 extends parallel to the seals [0, II and has upwardly angled wall portions, 28, 29, note FIG. 5, serving as guides and forming receptacle for the developing liquid. FIG. 1 shows that the intermediate base has steps 30, 3] arranged parallel to the sidewalls l4, which rest on seals l6, l7 and the steps have upwardly directed wall portions 32, 33.

The upper edges of wall portions 29, 32 and 33 are at a height so that they serve as supports for a main cover 34 whose vertical wall portions 35, 36, 37, 38, see FIGS. 1 and 5, terminate at the top of the device flush with the upper edges of the sidewalls ofthe base trough I.

A channel 39 is provided in the cover 34 defined at its periphery by the wall portions 35 to 38 and limited inwardly by a central, raised part of the cover 34. The channel 39 serves to collect any overspill ofliquid.

The trough-shaped base may have at certain points reinforcements 40 which collaborate with corresponding profiles 41 for aligning the intermediate base 24, note FIG. 3.

As shown in FIGS. 2, 3 and 4, the intermediate base 24 has a collecting chamber 42 open at its top with three holes 44, 45, 46 in its bottom 43. The hole 44, see FIG. I and FIG. 3, is located at the level of the lowest point of the dished portion of the intermediate base 24, and terminates in a socket 47 which serves both as discharge for the developing fluid reaching the intermediate base and as centering means. A centering pin or lug 48 with crossshaped cross section is engaged within this socket 47 and permits, by virtue of its configuration, free discharge of the liquid. The centering pin or lug 48 is mounted on the bottom 51 of the base trough l and is arranged obliquely by means of support legs 49, 50. A second centering member or lug 52, mounted on the bottom 5l, extends in the direction of the line connecting the two centering lugs 48, 52. The underside of the intermediate base 24 is provided with a fork-shaped profile 53, note FIG. 6, into which the upper end of the lug 52 engages, ensuring reliable alignment.

The hole 45 in the bottom of the collecting chamber 42 terminates in an upwardly directed socket 54 extending to near the upper surface of the device; two vertically spaced guide bushes 55, 56 for a shaft 57 ot'a pump body 58 are guided in this socket. These guide bushes will be described further below with reference to FIGS. 8 to II.

The shaft carries at its upper end one part 59 ofa dog clutch which engages with another clutch member when the develop ing device is fitted into an apparatus. The coupling member 60. see FIG. 2, is arranged so that it is automatically aligned with a drive member when the device is horizontally fitted.

A pump housing 6] is secured to the bottom 43 of the collecting chamber 42, e.g. by screws 62, 63. This pump housing covers the holes 44-46 and forms a channel between these holes (FIG. 1). The interengaging parts of the bottom 43 and of the pump housing 6l have overlapping edge webs. In addition, the pump housing 61 covers the pump body 58 and has thereunder an intake opening 64 arranged concentrically to the shaft 57, see FIGS. 1 and 2.

The hole 46 terminates in an upwardly extending tubular socket which passes through the collecting chamber 42; a tubular seal 66, 86 is engaged into this socket from the top and forms a seal by means of an annular flange 67.

Above the intermediate base 24 there is a trough-shaped insert comprised of a lower guide element 68 for the guide 69 for the copying material, shown in FIG. 5. This trough-shaped insert rests on supports on the component comprising the intermediate base 24. Its sidewalls 70, 71 note FIG. I, extend upwardly to the underside of the cover 34. It may be seen that the lower guide element 68 has guide webs 72, 73; 74, 75 formed along the guide and extending, as shown in FIG. 3, on either side of the centerline of the guide element, substantially in the direction of movement of the copying material but situated at a slight angle to the direction of movement so that the webs on both sides of the centerline gradually flare away from the centerline. This ensures that the copying material is held smooth.

In the trough-shaped insert in addition to the lower guide element 68, there is an upper guide element 76. This upper guide element 76 conforms to the shape of the lower guide element and has sidewalls 77, 78 adjacent the sidewalls 70, 71.

Above the hole 46 the guide elements 68, 76 each have a bulge in their respective sidewalls 71, 78. Wall portions of the bulge in the upper guide element 76 are shown in FIG. 2 at 79, 80, 81 and the wall portions in the zone of the bulge for the lower guide element are shown at 82, 83.

Between the wall portions 82, 83, the bottom of the lower guide element 68, has two holes 84, 85. Viewed as in FIG. 3, the hole 84 is offset towards the right but in the same plane as the hole 44 in the bottom 43 for the collecting chamber, permitting the liquid to flow downwardly therethrough into the trough formed by the base portion. The tubular seal 66, 86 (FIGS. 2 and 4) is fitted into the hoie 85. This seal projects downwardly with its part 87 extending into the tubular socket 65 and forming a seal. The other part 88 of the tubular seal 66-86 extends upwardly into a downwardly directed supply orifice 89 between the wall portions 80, 8I of the upper guide element 76. The upper ends of these wall portions form the defining walls ofa distributing channel, shown generally at 90 in FIG. 5 and extending parallel to the plane of the drawing in FIG. 4.

Between the wall portions 79, of the upper insert, the bulge has a downwardly directed hole 92 with a rim 91 at its lower end through which developing liquid flowing into the trough-shaped insert over the upper guide element '76 can be discharged downwardly into the trough in the base portion 1.

It follows from the preceding description that during the assembly of the components the connections between aligned parts are made automatically.

As shown in FIG. 5 the upper part of the trough-shaped insert formed by the upper guide element 76 has an upright obliquely extending wall 93, also shown in FIG. 3 and located to the right ofthe hole or orifice 92 in FIG. 2. The upper part of this wall defines on side of the distributing channel 90. The other side of the distributing channel is formed by a partition 94, also formed on the upper guide element 76 and equipped with equidistantly spaced, upwardly oriented open slots 95 (see FIG. 4). Between the walls 93,94 a bottom 136 of the dis tributing channel is located above the line of the arcuate surface formed by the upper guide element 76. To the right of the partition 94 as viewed in FIG. 5 the upper guide element 76 is extended by a section 96 terminating at 97 at a level which is lower than that of the other opposite end 98 of the upper guide element.

A cover 99 for the distributing channel is fitted over the top edges of walls 93, 94. This cover is shown from the bottom in FIG. 7 and its downwardly projecting rims 100, 10] fit between the walls 93, 94. The right-hand end of the cover 99, as viewed in FIG. 4 forms an arcuate connection 102 leading to the supply outlet 89 for the liquid developer supplied by the pump.

It may be seen from FIG. 7 that the supply or distributing channel 90, extending between the walls 93, 94 and the corresponding rims 100, I01, tapers towards the end remote from the arcuate connection 102, that is to say from the supply side.

The cover 99 is fixed by screws [03, [04, see FIG. 4, the screw 104 passing through an oblong hole 105 which permits ventilation.

Further, it may be seen in FIG. 5 that the rim l! overlaps the partition 94 between the distributing channel 90 and an adjacent calming chamber 106 so that the upper portions of slots 95 are covered and the flow cross section of the slots can be varied by adjusting the vertical position of the cover 99.

The cover 99 has a horizontal section l07 extending over the part 96 of the upper guide element 76 and defining therewith the calming chamber 106. At its free end the section [07 has a downwardly extending wall 108 which terminates at a small distance in front or to the right as viewed in FIG. of the adjacent end 97 of the upper guide element 76 and forming a slot-shaped outlet 109 for the liquid developer. This outlet has a smaller height than the slots 95; in particular its upper limit is lower than the upper edges of the slots. Moreover the slot-shaped opening 109 is conveniently located below the plane of the other end 98 of the upper guide element.

When the developer flows through the opening 109 into the guide 69 it returns via the end 98, forming an overflow to the upper side end 98 of the upper guide element and flows downwardly through the hole 92 and the connecting conduit back into the trough in the base portion 1.

Mounted on the lower surface of the upper guide element 76 is a guide member 110, for example of metal, conforming to the guide element over a certain length and equipped on its underside with guide ribs 11], H2 (FIG. 4). These guide ribs may extend in parallel relationship to the guide ribs 72 to 75 of the lower guide element. They may be formed in the guide element 110 as corrugations.

It can be seen from FIG. 5 that a transverse channel 113 extends under the bottom [36 of the distributing channel 90. Within the region of this transverse channel, which is open towards the bottom, the guide member 110 may be perforated in order to remove air from the developing liquid flowing through the guide 69. To this end the stiffening ribs ll] are omitted in the region of the channel 113 as shown in FIG. 4.

Between the sidewalls 70, 77 of the upper and lower guide elements and the outer wall of the base portion 1 and the wall 32 of the intermediate base 24, there is a free space which contains an orifice 114 through the main cover 34. Through this orifice the constituents of the developer may be recharged and flow through the intermediate base 24 into the trough of base portion 1.

The drawings also show means for supporting the individual part on one another. It may be seen that the assembly is effected with the automatic establishment of the flow connections if first the intermediate base 24 is fitted followed by the trough-shaped insert comprised of the guide elements 68, 76 and finally by the cover 34. During this assembly the pump mounted on the intermediate base 24 is also brought into positron.

The adjustment of the connection between the distributing channel 90 and the calming chamber I07, by fitting the cover 99 in a certain position, may be carried out previously.

After the assembly of these parts the clamping means are fitted into place. As shown in FIG. 2, these means consist of hooks 115, 116 at the upper ends of shanks 117, 118 reversely bent legs H9, 120 at their lower ends. The insides of the legs are provided with lugs 12], 122 which engage into the holes 20, 21 when these legs are introduced into the spaces 22, 23 behind the webs l8, 19 in an upward direction. Conveniently the distance between the lugs 12], 122 and the shanks H7, 118 is smaller than the width of the webs I8, 19 resulting in a perfectly reliable engagement. In front ofthe lugs 121, 122 the shanks 117, H8 may have recesses by means of which the legs H9, 120 can be spread by means of a tool and the clips can be removed. The fitting is facilitated by a top chamfer on the lugs l2l, 122.

It may be said with reference to FIG. 5 that the copying material is introduced through a hole 135 in the cover 34 at the end of the guide 69 at which the liquid is supplied from the distributing channel through the calming chamber 106.

FIGS. 8 to 11 show the guide bushes 55, 56 of FIG. 1 on an enlarged scale. They consist of two concentrically arranged radially spaced sleeves 123, 124 of which the outer sleeve 123 has a thinner wall than the inner sleeve 124. An annular space 134 is provided between the sleeves 123, 124. Both sleeves are connected, for example by three webs 125, 126, 127 offset by In addition the outer sleeve has mounting ribs 128, I29, I30 extending axially in the embodiment shown and not reaching over the entire height. On one end of the sleeves the webs [25 to 127 extends radially outwardly and carry a flangelike ring 131. lt may be seen that preferably the outer sleeve 123 is aligned with the annular opening 133 between the ring 131 and an upper flange 132 formed on the inner sleeve 124.

It may be seen that with a three-point support the inner sleeve 124 can adapt itself to an opening under a certain deformation. The webs 125, 126, I27 ensure the centering. These webs are preferably radially arranged but may also be oblique to the radial direction to permit a certain resilience. The mounting ribs 128 to may have helical configuration. in addition the spaces 133, 134 permit ventilation.

We claim:

1. A developing device for photoconductive copying material comprising walls forming a storage tank arranged to contain a supply of liquid developer with particles of pigment therein, means mounted on said storage tank and forming a longitudinally extending upwardly concave channellike guide having an inlet at one end for receiving the copying material and an outlet at the opposite end in the longitudinal direction for discharging the copying material after it passes through said channellike guide in which a continuous supply of liquid developer is provided for contact with the copying material as it passes therethrough, said means comprising a first guide element having an arcuate shape in the longitudinal direction of said channellike guide and defining the upper surface of said channellike guide and second guide element spaced closely below and having a configuration similar to said first guide elements so that said second guide element defines the lower surface of said channellike guide, a distributing channel for the liquid developer extending for and in the direction of the width of said channellike guide, a pump for delivering the liquid developer from said storage tank to said distributing channel from which the liquid developer flows into said channellike guide, and said means mounted on said storage tank providing an overflow from said channellike guide for returning the liquid developer to said storage tank after its passage through said guide and with the level of the overflow defining the liquid level in said channellike guide, wherein the improvement comprises means in combination with said first guide element for supplying liquid developer from said distributing channel into said channellike guide at a level below the liquid level in said guide and at a position located above the lowest level of said channellike guide and upstream from said overflow in the direction of movement of the copying material from the inlet to the outlet of said channellike guide so that coincident travel of the liquid developer and copying material is effected through said guide and any turbulence in the liquid developer is avoided, said overflow being formed at least by the downstream edge of said first guide element, the upstream edge of said first guide element being located above and upstream from the lowest level of said channellike guide, said first guide element being shorter in the longitudinal direction of said channellike guide than said second guide element and with the downstream edge of said first guide element being positioned upstream from the outlet from said channellike guide, said downstream edge of said first guide element located at a level below the inlet to said channellike guide, and said distributing channel located above said first guide element at a position spaced intermediate the upstream edge and downstream edge of said first guide element.

2. A developing device, as set forth in claim I, wherein the upstream edge of said first guide element is located within said channellike guide downstream from the inlet thereto and is positioned at a level below the downstream edge of said first guide element, said distributing channel extends in the direction of said upstream edge and is located adjacent thereto and said upstream edge forming at least the lower edge of an opening which in combination with said means for supplying liquid developer from said distributing channel affords communication with said channellike guide,

3, A developing device, as set forth in claim 2, wherein a portion of said first guide element adjacent the upstream edge thereof is spaced upwardly from and secured to the arcuately shaped portion of said first guide element and forms a bottom wall portion of said distributing channel.

4, A developing device, as set forth in claim 2, wherein said means for supplying liquid developer from said distributing channel into said channellike guide comprises a calming chamber extending in the direction of said distributing channel and the upstream edge of said first guide element, at least one connecting orifice being provided between said distributing channel and said calming chamber, and said calming chamber arranged for supplying the liquid developer at the inlet opening into said channellike guide where the lower edge of said opening is formed by said upstream edge of said first guide element.

5. A developing device, as set forth in claim 4, wherein said means for supplying liquiddeveloper comprises wall means in combination with the upstream edge of said first guide element forming a slotlike opening between said calming chamber and said channellike guide with said opening extend ing transversely across said guide, said slotlike opening having a height which is less than the height of the connecting orifice between said distributing channel and said calming chamber and the upper limit of said slotlike opening being located below the upper limit of the connecting orifice between said distributing channel and said calming chamber 6. A developing device, as set forth in claim 5, wherein a common partition wall separates said distributing channel and said calming chamber, said partition wall containing a plurality of oblong holes with vertical axis equally distantly spaced from one another for forming connecting orifices between said distributing channel and said calming chamber,

7. A developing device, as set forth in claim I, wherein said distributing channel comprises a pair of sidewall sections integral with and extending upwardly from the upper surface of said first guide element, a horizontal bottom wall section extending between said sidewall sections and spaced vertically upwardly from the line of the arcuately shaped surface of said first guide element, a section of said first guide element extending between its upstream edge and the adjacent one of said sidewall sections forming in combination with said adjacent sidewall section a part of a calming chamber, a plurality of connecting orifices formed in said adjacent one of said wide sidewall sections for communicating between said distributing channel and said calming chamber, a cover member extending over said distributing channel and forming the upper limits of said calming chamber. said cover member being supported on said sidewall sections, said cover member having a downwardly projecting wall portion extending toward but spaced vertically above the upstream edge of said first guide element and forming therewith a slot-shaped opening extending transversely across said channellike guide for affording communication between said calming chamber and said channellike guide, and said cover having a downwardly projecting rim located within said distributing channel and adjacent the surface of said sidewall section separating said distributing channel and said calming chamber and said rim covering at least the upper portion of said connecting orifices between said distributing channel and said calming chamber.

8. A developing device, as set forth in claim 1, wherein a metal guide member secured to the lower surface of said first guide element and extending from the upstream edge thereof in the direction of movement of copying material through said channellike guide toward the downstream edge thereof, said metal guide member having a plurality of ribs extending in the longitudinal direction of said channellike guide.

9, A developing device, as set forth in claim 8, wherein a portion of said first guide element being offset upwardly from the line of its arcuately shaped configuration for forming an open transverse channel extending for the width of said channellike guide, said channel being opened at its base and being aligned below said distributing channel, said metal guide member extending across the lower opened end of said transverse channel and said metal guide member being perforated in the portion spanning said transverse channel for forming vent openings between said channellike guide and said trans verse channel, and said transverse channel having an opening therefrom for venting gas collected in said transverse channel from said channellike guide.

10, A developing device, as set forth in claim 1, wherein up' wardly extending walls being secured to the opposite longitudinally extending edges of said first guide element forming a trough-shaped insert, upwardly extending walls being secured to the longitudinally extending side edges of said second guide element forming a trough-shaped insert arranged to receive the trough-shaped insert formed by said first guide element and its sidewalls therein, one said sidewall of said first guide element and the adjacent said sidewall of said second guide element being arranged to form a pair of aligned upwardly extending openings, one of said openings being arranged to supply the liquid developer from said storage tank into said distributing channel and the other said opening being arranged as a return conduit from the trough-shaped insert formed by said first guide element to said storage tank for returning liquid developer thereto after its flow through said channellike guide, a tubular seal being disposed in said open ing connecting said storage tank and said distributing channel, and the upper end of said other opening being located at the lowest point in said arcuately shaped first and second guide elements.

11. A developing device for photoconductive copying material comprising walls forming a storage tank arranged to contain a supply of liquid developer with particles of pigment therein, means mounted on said storage tank and forming a longitudinally extending upwardly concave channellike guide having an inlet at one end for receiving the copying material and an outlet at the opposite end in the longitudinal direction for discharging the copying material after it passes through said channellike guide in which a continuous supply of liquid developer is provided for contact with the copying material as it passes therethrough, said means comprising a first guide element having an arcuate shape in the longitudinal direction of said channellike guide and defining the upper surface of said channellike guide and a second guide element spaced closely below and having a configuration similar to said first guide elements so that said second guide elements defines the lower surface of said channellike guide, a distributing channel for the liquid developer extending for and in the direction of the width of said channellike guide, a pump for delivering the liquid developer from said storage tank to said distributing channel from which the liquid developer flows into said channellike guide, and said means mounted on said storage tank providing an overflow from said channellike guide for returning the liquid developer to said storage tank after its passage through said guide and with the level of the overflow defining ie liquid level in said channellike guide, wherein the im rovement comprises means for supplying liquid developer om said distributing channel into said channellike guide at a vel below the liquid level in said guide and at a position cated upstream from said overflow in the direction of moveent of the copying material from the inlet to the outlet of id channellike guide so that coincident travel of the liquid :veloper and copying material is effected through said chan- :llike guide and any turbulence in the liquid developer is oided, said overflow being formed at least by the iwnstream edge of said first guide element, the upstream ge of said first guide element being located above the lowest lei of said channellike guide, and said first guide element ing shorter in the longitudinal direction of'said channellike ide than said second guide element and with the wnstream edge of said first guide element being positioned stream from the outlet from said channellike guide, said l"S forming said storage tank comprising a trough-shaped se part comprised ofa bottom portion and upwardly extend gsidewalls secured to bottom portion, guide means disposed thin and secured to said trough-shaped base part, an inter- :diate base having a dish-shaped base portion arranged to :eive said guide means in said trough-shaped base part, said at guide element having sidewalls forming a trough-shaped ert, said second guide element having sidewalls forming a :ond trough-shaped insert into which said trough-shaped int formed by said first guide element is fitted, said first and :ond guide elements being supported on said intermediate e, said first guide element forming a collecting vessel exlding transversely across said device and having several enings therethrough, said intermediate base forming a wnwardly extending collecting chamber having a bottom ll section containing two openings, a first tubular wall ans connected at its lower end to one of the openings in d collecting chamber and extending upwardly through one the openings in said guide elements for forming a feed cont for supplying liquid developer to said distributing chanand a second tubular wall member forming an outlet cont for the liquid developer from the collecting vessel formed said first guide elements for supplying the developer vnwardly into said storage tank. 2. A device, as set forth in claim ll, wherein a pump houssecured to and extending downwardly from the bottom 1 section of said collecting chamber, said bottom wall sec 1 having a third opening, a pump shaft extending through 1 third opening, said pump housing located below and ning a closure for the openings in the bottom wall section said collecting chamber, said pump housing having an :ning therethrough in alignment with said pump shaft, and a ular socket concentrically disposed about said pump shaft extending upwardly from the bottom wall section of said ecting chamber to the level of the first guide element. 3. A developing device, as set forth in claim ll, wherein l guide means in the trough-shaped base part of said storage tank comprising a first centering lug and a second centering lug arranged to engage said intermediate base, said first centering lug having a longitudinally extending striplike shape and extending in the direction of aligned interconnecting said first and second centering lugs, said second centering lug having a pinshaped configuration and arranged to engage in the opening in the bottom wall section of said collecting chamber from which liquid developer is discharged into said storage tank, said second centering lug having a cross-shaped horizontal cross section, and a slot-shaped projection on the lower surface of said intermediate bass for engagement with the upper edge of said intermediate base for engagement with the upper edge of said first centering lug.

14. A developing device, as set forth in claim I], wherein a cover member positioned across and forming a closure on the upper end of said device for said intermediate base and said first and second guide elements, the peripheral edges of said cover member being supported on said intermediate base, and

detachable fixin means for securing said cover said first and second guide cements and said intermediate base on said storage tank, downwardly directed webs being formed on the periphery of said storage tank, said fixing means comprising vertically extending shanks, hooks formed on the upper ends of said shanks for engagement with the upper end of said storage tank wall sections and said cover member, and a hookshaped leg formed on the lower end of said shanks for engaging said downwardly directed webs, said downwardly directed webs having holes therethrough, and said fixing means having lugs thereon for engagement into the holes in said webs.

15. A developing device, as set forth in claim 14, wherein an upwardly directed U-shaped wall section is secured to the periphery of said cover and extends thereabout forming a circumferentially extending opened channel and an opening in said cover for providing communication to the interior of said intermediate base.

l6. A developing device, as set forth in claim 12, wherein a pair of vertically spaced bushes positioned within said tubular socket for guiding said pump shaft, each said bush comprising an inner sleeve in contact with said pump shaft and a concen trically arranged outer sleeve spaced radially outwardly from said inner sleeve and a plurality of angularly spaced longitudinally extending mounting ribs formed on the exterior sur face of said outer sleeve, and a plurality of angularly spaced radially extending webs located between said ribs and secured to said inner and outer sleeves.

17. A developing device, as set forth in claim 16, wherein a flange ring attached to the outer ends of said webs at one end of said sleeves, said ring being disposed radially outwardly from said outer sleeve and an annular orifice being formed between the inner surface of said ring and the outer surface of said inner sleeve and a continuation of said annular orifice being formed through said bush between the inner surface of said outer sleeve and the outer surface of said inner sleeve. 

1. A developing device for photoconductive copying material comprising walls forming a storage tank arranged to contain a supply of liquid developer with particles of pigment therein, means mounted on said storage tank and forming a longitudinally extending upwardly concave channellike guide having an inlet at one end for receiving the copying material and an outlet at the opposite end in the longitudinal direction for discharging the copying material after it passes through said channellike guide in which a continuous supply of liquid developer is provided for contact with the copying material as it passes therethrough, said means comprising a first guide element having an arcuate shape in the longitudinal direction of said channellike guide and defining the upper surface of said channellike guide and second guide element spaced closely below and having a configuration similar to said first guide elements so that said second guide element defines the lower surface of said channellike guide, a distributing channel for the liquid developer extending for and in the direction of the width of said channellike guide, a pump for delivering the liquid developer from said storage tank to said distributing channel from which the liquid developer flows into said channellike guide, and said means mounted on said storage tank providing an overflow from said channellike guide for returning the liquid developer to said storage tank after its passage through said guide and with the level of the overflow defining the liquid level in said channellike guide, wherein the improvement comprises means in combination with said first guide element for supplying liquid developer from said distributing channel into said channellike guide at a level below the liquid level in said guide and at a position located above the lowest level of said channellike guide and upstream from said overflow in the direction of movement of the copying material from the inlet to the outlet of said channellike guide so that coincident travel of the liquid developer and copying material is effected through said guide and any turbulence in the liquid developer is avoided, said overflow being formed at least by the downstream edge of said first guide element, the upstream edge of said first guide element being located above and upstream from the lowest level of said channellike guide, said first guide element being shorter in the longitudinal direction of said channellike guide than said second guide element and with the downstream edge of said first guide element being positioned upstream from the outlet from said channellike guide, said downstream edge of said first guide element located at a level below the inlet to said channellike guide, and said distributing channel located above said first guide element at a position spaced intermediate the upstream edge and downstream edge of said first guide element.
 2. A developing device, as set forth in claim 1, wherein the upstream edge of said fiRst guide element is located within said channellike guide downstream from the inlet thereto and is positioned at a level below the downstream edge of said first guide element, said distributing channel extends in the direction of said upstream edge and is located adjacent thereto and said upstream edge forming at least the lower edge of an opening which in combination with said means for supplying liquid developer from said distributing channel affords communication with said channellike guide.
 3. A developing device, as set forth in claim 2, wherein a portion of said first guide element adjacent the upstream edge thereof is spaced upwardly from and secured to the arcuately shaped portion of said first guide element and forms a bottom wall portion of said distributing channel.
 4. A developing device, as set forth in claim 2, wherein said means for supplying liquid developer from said distributing channel into said channellike guide comprises a calming chamber extending in the direction of said distributing channel and the upstream edge of said first guide element, at least one connecting orifice being provided between said distributing channel and said calming chamber, and said calming chamber arranged for supplying the liquid developer at the inlet opening into said channellike guide where the lower edge of said opening is formed by said upstream edge of said first guide element.
 5. A developing device, as set forth in claim 4, wherein said means for supplying liquid developer comprises wall means in combination with the upstream edge of said first guide element forming a slotlike opening between said calming chamber and said channellike guide with said opening extending transversely across said guide, said slotlike opening having a height which is less than the height of the connecting orifice between said distributing channel and said calming chamber and the upper limit of said slotlike opening being located below the upper limit of the connecting orifice between said distributing channel and said calming chamber.
 6. A developing device, as set forth in claim 5, wherein a common partition wall separates said distributing channel and said calming chamber, said partition wall containing a plurality of oblong holes with vertical axis equally distantly spaced from one another for forming connecting orifices between said distributing channel and said calming chamber.
 7. A developing device, as set forth in claim 1, wherein said distributing channel comprises a pair of sidewall sections integral with and extending upwardly from the upper surface of said first guide element, a horizontal bottom wall section extending between said sidewall sections and spaced vertically upwardly from the line of the arcuately shaped surface of said first guide element, a section of said first guide element extending between its upstream edge and the adjacent one of said sidewall sections forming in combination with said adjacent sidewall section a part of a calming chamber, a plurality of connecting orifices formed in said adjacent one of said wide sidewall sections for communicating between said distributing channel and said calming chamber, a cover member extending over said distributing channel and forming the upper limits of said calming chamber, said cover member being supported on said sidewall sections, said cover member having a downwardly projecting wall portion extending toward but spaced vertically above the upstream edge of said first guide element and forming therewith a slot-shaped opening extending transversely across said channellike guide for affording communication between said calming chamber and said channellike guide, and said cover having a downwardly projecting rim located within said distributing channel and adjacent the surface of said sidewall section separating said distributing channel and said calming chamber and said rim covering at least the upper portion of said connecting orifices between said distributing chAnnel and said calming chamber.
 8. A developing device, as set forth in claim 1, wherein a metal guide member secured to the lower surface of said first guide element and extending from the upstream edge thereof in the direction of movement of copying material through said channellike guide toward the downstream edge thereof, said metal guide member having a plurality of ribs extending in the longitudinal direction of said channellike guide.
 9. A developing device, as set forth in claim 8, wherein a portion of said first guide element being offset upwardly from the line of its arcuately shaped configuration for forming an open transverse channel extending for the width of said channellike guide, said channel being opened at its base and being aligned below said distributing channel, said metal guide member extending across the lower opened end of said transverse channel and said metal guide member being perforated in the portion spanning said transverse channel for forming vent openings between said channellike guide and said transverse channel, and said transverse channel having an opening therefrom for venting gas collected in said transverse channel from said channellike guide.
 10. A developing device, as set forth in claim 1, wherein upwardly extending walls being secured to the opposite longitudinally extending edges of said first guide element forming a trough-shaped insert, upwardly extending walls being secured to the longitudinally extending side edges of said second guide element forming a trough-shaped insert arranged to receive the trough-shaped insert formed by said first guide element and its sidewalls therein, one said sidewall of said first guide element and the adjacent said sidewall of said second guide element being arranged to form a pair of aligned upwardly extending openings, one of said openings being arranged to supply the liquid developer from said storage tank into said distributing channel and the other said opening being arranged as a return conduit from the trough-shaped insert formed by said first guide element to said storage tank for returning liquid developer thereto after its flow through said channellike guide, a tubular seal being disposed in said opening connecting said storage tank and said distributing channel, and the upper end of said other opening being located at the lowest point in said arcuately shaped first and second guide elements.
 11. A developing device for photoconductive copying material comprising walls forming a storage tank arranged to contain a supply of liquid developer with particles of pigment therein, means mounted on said storage tank and forming a longitudinally extending upwardly concave channellike guide having an inlet at one end for receiving the copying material and an outlet at the opposite end in the longitudinal direction for discharging the copying material after it passes through said channellike guide in which a continuous supply of liquid developer is provided for contact with the copying material as it passes therethrough, said means comprising a first guide element having an arcuate shape in the longitudinal direction of said channellike guide and defining the upper surface of said channellike guide and a second guide element spaced closely below and having a configuration similar to said first guide elements so that said second guide elements defines the lower surface of said channellike guide, a distributing channel for the liquid developer extending for and in the direction of the width of said channellike guide, a pump for delivering the liquid developer from said storage tank to said distributing channel from which the liquid developer flows into said channellike guide, and said means mounted on said storage tank providing an overflow from said channellike guide for returning the liquid developer to said storage tank after its passage through said guide and with the level of the overflow defining the liquid level in said channellike guiDe, wherein the improvement comprises means for supplying liquid developer from said distributing channel into said channellike guide at a level below the liquid level in said guide and at a position located upstream from said overflow in the direction of movement of the copying material from the inlet to the outlet of said channellike guide so that coincident travel of the liquid developer and copying material is effected through said channellike guide and any turbulence in the liquid developer is avoided, said overflow being formed at least by the downstream edge of said first guide element, the upstream edge of said first guide element being located above the lowest level of said channellike guide, and said first guide element being shorter in the longitudinal direction of said channellike guide than said second guide element and with the downstream edge of said first guide element being positioned upstream from the outlet from said channellike guide, said walls forming said storage tank comprising a trough-shaped base part comprised of a bottom portion and upwardly extending sidewalls secured to bottom portion, guide means disposed within and secured to said trough-shaped base part, an intermediate base having a dish-shaped base portion arranged to receive said guide means in said trough-shaped base part, said first guide element having sidewalls forming a trough-shaped insert, said second guide element having sidewalls forming a second trough-shaped insert into which said trough-shaped insert formed by said first guide element is fitted, said first and second guide elements being supported on said intermediate base, said first guide element forming a collecting vessel extending transversely across said device and having several openings therethrough, said intermediate base forming a downwardly extending collecting chamber having a bottom wall section containing two openings, a first tubular wall means connected at its lower end to one of the openings in said collecting chamber and extending upwardly through one of the openings in said guide elements for forming a feed conduit for supplying liquid developer to said distributing channel, and a second tubular wall member forming an outlet conduit for the liquid developer from the collecting vessel formed by said first guide elements for supplying the developer downwardly into said storage tank.
 12. A device, as set forth in claim 11, wherein a pump housing secured to and extending downwardly from the bottom wall section of said collecting chamber, said bottom wall section having a third opening, a pump shaft extending through said third opening, said pump housing located below and forming a closure for the openings in the bottom wall section of said collecting chamber, said pump housing having an opening therethrough in alignment with said pump shaft, and a tubular socket concentrically disposed about said pump shaft and extending upwardly from the bottom wall section of said collecting chamber to the level of the first guide element.
 13. A developing device, as set forth in claim 11, wherein said guide means in the trough-shaped base part of said storage tank comprising a first centering lug and a second centering lug arranged to engage said intermediate base, said first centering lug having a longitudinally extending striplike shape and extending in the direction of aligned interconnecting said first and second centering lugs, said second centering lug having a pin-shaped configuration and arranged to engage in the opening in the bottom wall section of said collecting chamber from which liquid developer is discharged into said storage tank, said second centering lug having a cross-shaped horizontal cross section, and a slot-shaped projection on the lower surface of said intermediate base for engagement with the upper edge of said intermediate base for engagement with the upper edge of said first centering lug.
 14. A developing device, as set forth in claim 11, wherein a cover membeR positioned across and forming a closure on the upper end of said device for said intermediate base and said first and second guide elements, the peripheral edges of said cover member being supported on said intermediate base, and detachable fixing means for securing said cover said first and second guide elements and said intermediate base on said storage tank, downwardly directed webs being formed on the periphery of said storage tank, said fixing means comprising vertically extending shanks, hooks formed on the upper ends of said shanks for engagement with the upper end of said storage tank wall sections and said cover member, and a hook-shaped leg formed on the lower end of said shanks for engaging said downwardly directed webs, said downwardly directed webs having holes therethrough, and said fixing means having lugs thereon for engagement into the holes in said webs.
 15. A developing device, as set forth in claim 14, wherein an upwardly directed U-shaped wall section is secured to the periphery of said cover and extends thereabout forming a circumferentially extending opened channel and an opening in said cover for providing communication to the interior of said intermediate base.
 16. A developing device, as set forth in claim 12, wherein a pair of vertically spaced bushes positioned within said tubular socket for guiding said pump shaft, each said bush comprising an inner sleeve in contact with said pump shaft and a concentrically arranged outer sleeve spaced radially outwardly from said inner sleeve and a plurality of angularly spaced longitudinally extending mounting ribs formed on the exterior surface of said outer sleeve, and a plurality of angularly spaced radially extending webs located between said ribs and secured to said inner and outer sleeves.
 17. A developing device, as set forth in claim 16, wherein a flange ring attached to the outer ends of said webs at one end of said sleeves, said ring being disposed radially outwardly from said outer sleeve and an annular orifice being formed between the inner surface of said ring and the outer surface of said inner sleeve and a continuation of said annular orifice being formed through said bush between the inner surface of said outer sleeve and the outer surface of said inner sleeve. 